The bridge will be closed between 9.30am and 2pm on Wednesday. Photo: Melissa Adams

NCA asset manager Peter Beutel said one of the covers on the road and bicycle lanes was making a loud sound as cars travelled across the bridge. ''It's not a major job but it has the potential to inconvenience people, particularly those headed to the zoo,'' he said.

Mr Beutel said the covers on the road were too heavy to be lifted manually so a crane would be required to remove them to allow inspectors to enter a chamber beneath the road.